betza grammar

betza-notation    → subpiece+
subpiece          → component | bent-type "[" component+ "]" long-length?
bent-type         → "t" | "g"
component         → diag | orth | hippo | queen | king

hippo             → other-modifiers* hippo-directions? hippo-piece length?
hippo-piece       → "N", "L", "J"
hippo-directions  → "ff" | "fs" | "fh" | "rr" | "rv" | "rh" | "ll" | "lv" | "lh" | "bb" | "bs" | "bh"

orth              → other-modifiers* orth-directions? (orth-stepper long-length? | orth-rider)
orth-stepper      → "W" | "D" | "H"
orth-rider        → orth-repeat-rider | orth-pure-rider length?
orth-repeat-rider → "WW" | "DD" | "HH"
orth-pure-rider   → "R"
orth-directions   → "f" | "r" | "l" | "b" | "fr" | "fl" | "fb" | "rl" | "rb" | "frl" | "frb" | "fbl" | "rlb"

diag              → other-modifiers* orth-directions? (diag-stepper long-length? | diag-rider)
diag-stepper      → "F" | "A" | "G"
diag-rider        → diag-repeat-rider | diag-pure-rider length?
diag-repeat-rider → "FF" | "AA" | "GG"
diag-pure-rider   → "B"
diag-directions   → "f" | "b" | "r" | "l"

queen             → other-modifiers* orth-directions? "Q" long-length
king              → other-modifiers* orth-directions? "K"

other-modifiers   → "c" | "hh" | "j" | "m" | "n" | "p" # also z | q | o | g but those are horrible

length            → {positive integers}
long-length       → {positive integers greater than 1}